Alex Rodriguez has become the Phantom of the Clubhouse, hardly ever seen by his locker during times the room is open to outsiders.

Other players’ high-tech stalls at the new Yankee Stadium are filled with family photos or personalized in some way. Not A-Rod’s.

For much of the last month, the only momento was a baseball in a plastic case. A bottle of bubbly was added during the last homestand.

Following more distractions in his first five seasons with the Yankees than most players have in their careers — from his ties to Madonna to the photo shoot where he kissed his reflection in a mirror — A-Rod appears to be all business. His spring training news conference to admit steroids use and subsequent hip surgery seems to have changed his outlook. Having survived those ordeals, he is far more relaxed.

He homered on his first swing of the season, waking the Yankees from a 13-15 start when he returned from the surgery, and hit a grand slam on his last as the team finished at 103-59.

“I hit rock bottom this spring, between the embarrassment of the press conference and my career being threatened with my hip injury,” he said Sunday in the visitor’s dugout at Tampa Bay. “I think my life, my career, was at a crossroads. I was going to stay at the bottom or I was going to bounce back.”

Rodriguez then went out and had the greatest offensive inning in American League history, hitting a three-run homer and a slam to reach 30 homers and 100 RBIs for the 12th consecutive year and 13th time overall.

Six of his RBIs during the season tied games and 29 more put the Yankees ahead, according to STATS LLC.

That’s fine in the eyes of most Yankees’ fans, but right now they’re more concerned with fall flops than summer success. He is 8-for-59 (.136) in the postseason dating to 2004 and is hitless in his past 18 playoff at-bats with runners in scoring position.

If the Yankees are to win their first World Series title since 2000 — and if A-Rod is to even make it to the series for the first time in 16 major league seasons — he is going to have to perform more like Mr. October, Reggie Jackson, than Mr. May, Dave Winfield, as the postseason stretches past Halloween into November.

“People talk about the failures of one guy, but one guy does not win a series or lose a series,” Joe Girardi said. “When I look at the last playoff, there were a lot of guys who didn’t hit. And because he’s the biggest name, or people like to talk about him the most, everyone focuses on his numbers.”

That’s what a record $275 million, 10-year contract will do.

Rodriguez famously opted out of his previous deal, a then-record $252 million, 10-year agreement, after going 4-for-15 (.267) with one RBI during the Yankees’ first-round loss to Cleveland in 2007. He won his third AL MVP award in five seasons after hitting 54 homers with 156 RBIs, but his October failures got more attention.

After torn cartilage in his right hip was repaired on March 9, Rodriguez wondered whether he would make it back on the field before August or September. He says he was surprised when he played his first game on May 8 at Baltimore.

“Right now I’m playing with house’s money, basically. I feel like I have nothing to lose,” he said. “From where I was 4½, five months ago in a bed in Colorado, it’s very easy to remember where I was.”

Playing on a roster that produced a team-record 244 homers and 915 runs — up from 789 last year — also has helped.

“Everybody is benefiting from each other’s ability to contribute,” general manager Brian Cashman said. “I think it takes a lot of heat off each individual knowing that somebody else is also there, so Alex doesn’t have to carry this team.”

New Yankee Stadium has been a benefit. While the old clubhouse had a puny players’ lounge and a tiny trainers’ room that reporters could peer into, the new home complex stretches from the plate down to the right-field foul pole. Players can disappear to into a large lounge, a sumptuous swimming pool or a wide weight room. There are even out-of-sight lockers to change in.

“It’s good exercise for the manager trying to find people,” Girardi said.

Following his divorce settlement last year, he’s been seen with actress Kate Hudson, who has watched several games at Yankee Stadium from a front-row seat. At 34, he seems happier than in the past, and players say he’s more at ease with himself.

“I know he is having a lot of fun this year,” said Mark Teixeira, A-Rod’s teammate on the 2003 Texas Rangers. “He’s been great with all of us. He’s just been one the guys.”